Field of the Invention
The present invention relates to a process and apparatus for cleaning imprinting molds, and a process for manufacturing a mold using that cleaning process.
Description of the Prior Art
In recent years, attention has been directed to nanoimprint technology for microprocessing including nanoprocessing. Nanoimprint technology is a sort of pattern-formation technique wherein a mold member including a substrate having an uneven structure formed on its surface is used to transfer the uneven structure on the mold onto a workpiece thereby transferring the uneven structure in the equal size.
The aforesaid nanoimprint technology known in the art includes a photoimprint method and a thermal imprint method. In the photoimprint method, for instance, a photocurable resin layer is formed as a workpiece on the surface of the substrate, and a mold having the desired uneven structure is pressed against the resin layer. In this state, the resin layer is irradiated with light from the mold side to cure the resin layer, after which the mold is pulled apart from the resin layer, whereby an uneven structure (uneven pattern) that is an inverted one of the uneven pattern the mold has can be formed on the resin layer that is the workpiece. In the thermal imprint method, the mold is pressed against the resin layer that is softened by heating, and the resin layer is then cooled down for curing, after which the resin layer is released from the mold.
For such an imprinting mold, there may be a copy mold used that is prepared as follows. For instance, a mask is formed on a substrate of quartz glass or silicon by means of electron beam lithography, and this mask is used to apply precise fine processing to a substrate of quartz glass or silicon by means of dry etching, thereby preparing a master mold. Then, this master mold is used to form a mask on a substrate of quartz glass or silicon by the imprint method, and this mask is used to apply precise fine processing to a substrate of quartz glass or silicon to prepare a copy mold (Patent Publication 1).
With imprinting molds inclusive of such master and copy molds, there may be deposition of the material to be patterned or the like during imprinting. To prevent this, a release agent such as a fluorine-based resin is coated on the surface to form a release layer thereby imparting releasability to it. However, a problem with such a release layer is that its releasability decreases with an increasing number of repetitive use of the mold; so there is some limitation on how often the mold is repetitively used or, in another parlance, the mold cannot stand up to thousands of repetitive use. For this reason, it has been proposed to treat a fluorine resin or other release layer that is formed on the mold by means of a cleaning agent or gas for its cleaning and removal, and then form a fresh release layer for the regeneration of the mold (Patent Publication 2).